KR102453447B1 - Injector for dispensing fluid with tapered inlet area of passage opening - Google Patents

Abstract

The present invention relates to an injector for injecting a fluid, said injector comprising: a valve seat (3) on which a sealing area is arranged; and a closing element (5) disposed on the injector central axis (X-X) and opening and closing at least one passageway opening (30) in the valve seat (3), said at least one passageway opening (30) being said injector center the main axis 300 at a set angle β with respect to the axis X-X, wherein the at least one passage opening 30 comprises an inlet area 41 , the inlet area 41 being tapered.

Description

Injector for dispensing fluid with tapered inlet area of passage opening

The present invention relates to an injector for fluid injection, in particular for fuel injection, with reduced pressure drop and a self-centering closing element of the valve seat.

Injectors for injecting a liquid, such as a fuel, into a volumetric space, such as an internal combustion engine, are known. Conventional designs include a housing with a movable closing element, for example a valve needle, adapted to each valve seat to open and close the injector, controlled for example by an electromagnet such as a piezoelectric actuator or solenoid valve. .

The prior art of injection involves the injection of a fluid into the combustion chamber through typically multiple passage openings opened by an inwardly opening valve needle. In the combustion chamber, an ignitable air-fuel mixture is formed and ignited.

In this case, for manufacturing technical reasons, the passage openings typically have to be manufactured, for example laser drilled, or corroded from the outer face to the inner face of the injector. This results in the formation of a sharp-edged inner surface of the passage hole, resulting in a high pressure drop and a high flow loss. In addition, this leads to deviations from the ideal central motion of the movable closing element and decentricity, in particular drift, of the closing element, especially in the case of high-pressure injection. In this case, even the slightest deviation or tilt of the injector can cause fluctuating behavior, which does not lead to an optimal spray image of the injected fluid. This adversely affects emissions and fuel economy, for example in the case of fuel.

It has also been found that the decentricity, in particular drift, of the movable closing element has a negative effect on the wear behavior of the injector.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an injector for fluid injection in which a reduction in pressure drop, a self-centering closing behavior of the closing element, and a reduction in flow losses are achieved.

An injector according to the invention for fluid injection, in particular for fuel injection, having the features of claim 1 has the advantage that a reduction in pressure drop, a self-centering closing behavior of the closing element of the valve seat, and a reduction in flow losses are achieved. Due to this, excessive wear of the closing element can be prevented. In addition, the spray image of the volumetric space, in particular of the fluid injected into the combustion chamber, can be maintained with significantly larger and smaller deviations from the set behavior with respect to the droplet size distribution and trajectory. The invention therefore has the advantage of advantageously affecting the hydrodynamic conditions in the spraying region in order to optimize the spraying and/or the inlet behavior of the sprayed fluid downstream of the valve seat.

In the case of a preferred fuel injector, this also has a favorable effect on the operating behavior of the internal combustion engine and a significant reduction in exhaust gases. In addition, maintenance intervals and service life are very positively extended.

All these advantages are achieved by an injector according to the invention for dispensing a fluid comprising a closing element and a valve seat on which a sealing area is arranged. In this case, a closing element, for example a linearly movable valve needle, is arranged on the injector central axis and is moved to open and close again the geometry of at least one passage opening, often a plurality of passage openings, in the valve seat. In this case, the at least one passage opening comprises a main axis at a set angle with respect to the injector central axis. Further, the at least one passage opening includes an inlet region, the inlet region being tapered.

The dependent claims present preferred embodiments of the invention.

In a preferred embodiment, the flow cross-section of the inlet region, transverse to the main axis, decreases continuously in the flow direction. It is also preferred that in the inflow region tapered from the front to the rear when viewed in the flow direction there is at least one section in which the flow cross-section is kept constant, so that in each section, the cylindrical circumferential shape of the inflow region tapered as a whole appears. can do. Additionally or alternatively, the inlet region tapered in the flow direction may comprise a profiled, eg wavy and/or stepped inner circumferential face.

Preferably, the inlet area can be designed as an inner hollow cone with a cone angle α of the inner wall relative to the central axis of the cone, as in a funnel. Even in this case, the inner circumferential surface of the inner hollow cone can be designed not only to be smooth, but also to be designed to be profiled.

Further, it is preferable that the central axis of the cone intersects the main axis of the passage opening at an inclination angle ?.

In the geometrically simplest case, which should not be considered as limiting of the invention, preferably the central axis of the cone coincides with the major axis of the passage opening. This corresponds to the inclination angle δ chosen to be zero. In this possible embodiment, in a cross-section with a plane E1 defined by the inlet flow cross-section of the inlet region according to the definition within the scope of the invention, a circular inlet circumferential contour is formed in said same plane E1 .

Thus, the circle center point of the circular inlet circumferential contour lies at the intersection of the cone central axis or main axis and the plane E1.

This gives many other advantages in terms of the various aspects of the operational behavior of the injector itself, which are made downstream, in particular in hydrodynamic and/or thermal and/or mechanical processes.

Furthermore, the inlet flow cross-section of the inlet region defining the plane E1 may have an inlet circumferential contour in said same plane, preferably a non-circular plane E1 . In principle, any type of non-circular inlet circumferential contour can be designed. This is because, in modern 3D controlled machine manufacturing machines, several degrees of freedom of the tool to implement the contour can be controlled separately. Within the scope of the present invention, contouring tools are, in addition to cutting tools known in the prior art, for example milling heads, corrosion punches, electric discharge machining and/or laser processing.

By use of the 3D degree of freedom, non-circular circumferential contours characterized by convex subregions and concave subregions can be formed.

In a particularly preferred embodiment of the non-circular inlet circumferential contour, said contour is designed to be elliptical in the plane E1 . This is achieved, in a preferred embodiment, by the rotationally symmetrical inner hollow cone being geometrically arranged at an angle of inclination δ with respect to the main axis of the passage opening. Thus, the elliptical receiving contour corresponds to the cross-sectional image in the plane E1.

However, in other embodiments, as an alternative, it may be desirable for the inner hollow cone to be asymmetric rather than rotationally symmetric with respect to the central axis of the cone and not designed with a constant cone angle α of the inner wall.

On the other hand, it may be desirable for the inner hollow cone to comprise different partial sections of the inner wall with various cone angles α. These partial sections of the inner wall can be defined according to the circular angle as follows.

First, in the inlet circumferential contour of the plane E1, the first circumferential point A closest to the major axis of the passage opening, i.e. the circumferential point A, at which the circular angle γ is zero in the plane E1 about the major axis. this is decided Thus, the first circumferential point A is used, for example, as an initial coordinate for a circular angle γ in a clockwise direction about the main axis.

In a preferred embodiment, the cone angle α varies with the circular angle γ.

In the case of a non-circular inlet circumferential contour, also at least one second circumferential point B furthest from the main axis of the passage opening should be given. This may be arranged at an arbitrary circular angle γ with respect to the first circumferential point A in the plane E1 according to an embodiment. In a particularly preferred embodiment, the second circumferential point B is at a circular angle γ of 180° with respect to the first circumferential point A.

Furthermore, the inlet region is preferably designed in the form of an asymmetrically distorted inner hollow cone.

This is, in another preferred embodiment, convex, ie at least one first partial section designed with increasing cone angle α, for example a circle between the first circumference point A and the second circumference point B. In the angular segment, at least one further partial section designed concave, ie with a decreasing cone angle α, is given by succession.

The further partial section may be, for example, a single further partial section between the second circumferential point B and the first circumferential point A, closing the circumference to form a complete circle. As an alternative, a further partial section starting at the second circumferential point B may be followed by a further convex or concave partial section.

A preferred embodiment is described for a varying inlet circumferential contour of the inlet area in the plane E1 according to the circular angle γ.

According to a preferred refinement, the passage opening is divided into individual regions characterized by different flow cross-sections. Thereby, downstream of the tapered inlet region, in the intended form for flow through the entire passage opening, more of the disadvantages of the prior art can be eliminated.

The passage opening preferably comprises an intermediate flow region having an intermediate flow cross-section downstream of the inflow region as viewed in the flow direction. Furthermore, the passage opening preferably comprises an outlet flow region having an outlet flow cross-section downstream of the intermediate flow region.

In this case, it is particularly preferable for the narrowest flow cross-section of the passage opening to lie in the region of the intermediate flow cross-section.

Preferably, the intermediate flow region and/or the outlet flow region are designed to be cylindrical with respect to the main axis. The advantage of the cylindrical design lies in its simple manufacture, for example by means of a rotating drilling head or a milling head.

However, this should not be construed as limiting the present invention. This is because, in particular depending on the rheology of the fluid to be sprayed, it may be desirable for the intermediate flow region and/or the outlet flow region to be designed with a variable flow cross-section, in particular tapered or conversely enlarged again.

Furthermore, the dimensions of the regions with different flow cross-sections can be designed in relation to each other and varied, but intentionally.

Accordingly, it is preferred that the inlet region defines an inlet length, the intermediate flow region defines an intermediate length, and the outlet flow region defines an outlet length. It may be particularly preferable for the inlet length and the intermediate length to be similar or identical to each other. Additionally or alternatively, the outlet length may be greater than the inlet length and/or intermediate length. In this case, the relationship between the discharge length and at least one of the last mentioned lengths may be chosen to differ by about a factor of 1.3 to 2.3, more preferably 1.4 to 1.7.

It is particularly preferred that the injector according to the invention is a fuel injector for fuel injection, in particular for liquid fuel injection.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a schematic cross-sectional view of an injector according to a preferred embodiment of the present invention;
FIG. 2 is a schematic enlarged cross-sectional view of the valve seat of the injector of FIG. 1 including passage openings; FIG.
Fig. 3 is a schematic enlarged cross-sectional view of the passage opening of Fig. 2;
Fig. 4 is a schematic plan view of the inflow area of the passage opening of Fig. 3 in the flow direction;

In different drawings, the same reference numerals each refer to the same element.

1 and 2 , the injector 1 according to the preferred embodiment of the present invention includes a valve housing 2 and a valve seat 3 . The valve seat 3 is fixed to the valve housing 2 by means of a form-fit connection, for example.

The injector further comprises a closing element 5 in this preferred embodiment in the form of a valve needle linearly movable along the central axis X-X of the injector in the axial direction of the injector. The injector 1 also comprises a restoring element 6 in the form of a mechanical spring in this embodiment, which retains the closing element 5 in the closed position shown in FIG. 1 .

The closing element 5 is actuated by an actuator 7 , in this embodiment a magnetic actuator. Reference numeral 8 denotes an electrical connection.

Fuel is guided from the inside of the injector 1 to the end of the closing element 5 on the valve seat 3 .

1 or 2 , the valve seat 3 is for example arranged in front of the free injection volume (not fully shown here) towards the combustion chamber, and the fluid to be injected, such as fuel, in the unclosed valve state. injected into the combustion chamber.

In particular, as shown in FIG. 2 , the valve seat 3 has a plurality of passage openings 30 that can be opened and closed by a closing element 5 on the sealing seat 50 . Like FIG. 1 , FIG. 2 also shows the closed state of the injector.

Also, as shown in FIG. 2 , in this embodiment, the sealing seat 50 in the valve seat 3 is located on the injection side of the closing element 5 , here at the end embodied as a valve ball, in a small volume fluid reservoir. It further includes a region 40 . In this case, the fluid reservoir area 40 is designed as a flat recessed area into the sealing sheet 50 .

The optionally provided fluid reservoir region 40 serves primarily to keep the thin fluid film flowing. This ensures in particular continuous wetting and a more uniform local pressure behavior.

In the cross-section shown here, two passage openings 30 appear in the cross-section shown in the cross-section, which basically corresponds to a possible embodiment.

In this case, the two passage openings 30 have respective main axes 300 .

The major axis 300 of the passage opening 30 forms a set angle β with respect to the injector central axis X-X. In the embodiment shown here, the set angle β for the two passage openings 30 is equal to 30°.

However, in principle, at least one or each of the passage openings 30 can be arranged at a different set angle β.

The passage openings 30 are perfused in the respective flow direction 200 by the fluid to be sprayed (see FIGS. 2 and 3 ).

Individual jets of liquid (not shown here) occurring per passage opening 30 are generally the finest primary and secondary due to the breaking effect due to flow disruption by their respective circumferential inner walls and discharge edges during their flow discharge. It is formed as a so-called spray projection made of tea drops.

3 shows a cross-sectional view of the passage opening 30 as a detail of FIG. 2 . FIG. 4 in conjunction with FIG. 3 shows a corresponding top view of the passage opening 30 arranged in the sealing sheet 50 when viewed in the flow direction 200 .

In particular, the geometrical arrangement with respect to each set angle β and the internal design of the passage opening 30 have a hydrodynamic influence on the flow behavior of the fluid through the passage opening 30 and its jetting behavior downstream.

As can be seen in particular by the preferred embodiment of the passageway opening 30 , shown in FIG. 3 , each inner flow cross-section 550 is variable along the flow direction 200 .

In this case, a total of four individual flow regions 40 , 41 , 42 , 43 are distinguished which are characterized by different flow cross sections.

On the one hand, the passage opening 30 is preferably arranged in an existing fluid reservoir region 40 .

In this case, the fluid reservoir region 40 is recessed into the sealing sheet 50 in the form of a flat convex vat, from which the fluid reservoir length L0 along the major axis 300 of the passage opening 30 corresponds to the vat depth. ) is given.

Perpendicular to the main axis 300 , a cut plane, denoted as plane E2 of the fluid reservoir region 40 , appears in the sealing sheet 50 with the fluid reservoir flow cross-section 500 .

The fluid reservoir flow cross-section 500 displays a fluid reservoir circumferential contour 600 in a plane E2 at its periphery.

Also, as shown in FIG. 3 , the passage opening 30 is subdivided into its three flow regions 41 , 42 , 43 .

Accordingly, the passage opening 30 shown in FIG. 3 includes an inlet region 41 having an inlet flow cross-section 501 downstream of the fluid reservoir region 40 when viewed in the flow direction 200 .

By definition, the inlet flow cross-section 501 of the inlet region 41 lies within the cut-away plane of the valve seat 3 marked as plane E1 . The plane E1 is a plane offset parallel to the plane E2 and thus perpendicular to the main axis 300 .

In the plane E1 , the inlet flow cross-section 501 represents at its circumference the inlet circumferential contour 601 of the inlet region 41 .

It should be noted here that at least one inner body edge of the passage opening 30 , in particular at least one circumferential contour 600 , 601 , 602 , is arranged in the inlet region 41 and/or the fluid reservoir region 40 . ) may include small radii and/or 45° chamfers. Thus, the rounded flow-through region serves to reduce hydrodynamically undesirable effects such as flow disruption and/or cavitation.

3 and 4 , the inlet flow cross-section 501 of the inlet region 41 is smaller than the fluid reservoir flow cross-section 500 of the fluid reservoir region 40 . Also, in the direction of projection about the main axis 300 , the circumferential contours 600 , 601 do not intersect as the inlet flow cross section 501 falls completely into the larger fluid reservoir flow cross section 500 .

It should be noted that this geometrical arrangement should not be construed as limiting the present invention. In another preferred embodiment, the inlet flow cross-section 501 falls into the larger fluid reservoir flow cross-section 500 by at least a majority of the area, preferably greater than 90%.

The passage opening 30 also includes an intermediate flow region 42 having an intermediate flow cross-section 502 downstream of the inlet region 41 when viewed in the flow direction 200 .

The passage opening 30 also includes an outlet flow region 43 having an outlet flow cross-section 503 downstream of the intermediate flow region 42 when viewed in the flow direction 200 .

Also, as can be seen from FIG. 3 , the inlet length L1 for the inlet region 41 , the intermediate length L2 for the intermediate flow region 42 , and the outlet length L1 for the outlet flow region 43 . L3) is given.

In this case, the intermediate flow region 42 along the total intermediate length L2 and the outlet flow region 43 along the total exhaust length L3 are designed cylindrically with respect to the main axis.

Here, the narrowest flow cross-section 550 of the passage opening 30 lies within the intermediate flow region 42 and thus is determined by the intermediate flow cross-section 502 .

In this regard, as can be seen particularly well from FIG. 3 , in this preferred embodiment, the passage opening 30 is disposed downstream of the inlet flow region 41 in the flow direction thereof by means of an inner shoulder in the flow direction ( 200) and is designed as a typical circular bore with an enlarged cross-section.

In a preferred embodiment, the inlet length L1 and the intermediate length L2 are similar or the same size. Also, the outlet length L3 is approximately equal in size to or equal to the total length of the inlet length L1 and the intermediate length L2 in size.

According to the invention, a tapered design of the inlet region 41 of the at least one passage opening 30 has been shown to be particularly advantageous. Accordingly, the inlet flow cross-section 501 is chosen to be larger than the intermediate flow cross-section 502, as shown in the passage opening 30 shown identically in FIGS. 1-3.

It can also be seen that, in the preferred embodiment shown here, the flow cross-section 550 continuously decreases over the length L1, ie, from the inlet flow cross-section 501 to the intermediate flow cross-section 502, in a linear gradient. have.

Thus, in particular as shown in FIG. 3 , the inlet region 41 tapered in the form of a funnel can in particular appear as an inner hollow cone defined by the cone angle α of the inner wall with respect to the central cone axis 800 .

In particular, as shown in FIG. 3 , the aforementioned linear gradient is determined not only by the cone angle α, but also by the inclination angle δ.

This is because the angle of inclination δ represents the angle of intersection between the central axis of the cone 800 and the main axis 300 of the passage opening 30 . Thus, the angle of inclination δ relates to a measure of the disposition of the inner hollow cone of the tapered inlet region 41 in the form of a funnel in FIG. 3 with respect to the major axis 300 of the passage opening 30 .

In particular, the cone angle α and the inclination angle δ are decisive for the geometry of the tapered inlet region 41 of the passage opening 30 and thus the inflow behavior of the injected fluid.

It should be noted in this case that in an alternative embodiment not shown here, the inclination angle δ may be selected to be zero, so that the central axis of the cone 800 and the major axis 300 of the passage opening 30 coincide. will be. In this alternative embodiment, a circular inlet circumferential contour 601 of the inlet region 41 appears in a section having a plane E1 defined by the inlet flow cross-section 501 . In this case, the circle center M of the circular inlet circumferential contour 601 lies at the intersection of the cone central axis 800 or main axis 300 and the plane E1 .

However, in conjunction with the related drawings in FIG. 4 , in FIG. 3 , there is a preferred embodiment in which the geometrical arrangement of a rotationally symmetrical inner hollow cone arranged at an inclination angle δ of about 10 degrees with respect to the main axis of the passage opening is shown.

From the cross section of an obliquely arranged inner hollow cone with the plane E1 of the inlet flow cross section 501 , an elliptical inlet circumferential contour 601 is geometrically formed.

The elliptical inlet circumferential contour 601 is particularly well represented in FIG. 4 .

Furthermore, in FIG. 4 the positions according to the definition of the two marking points A, B are indicated along the inlet circumferential contour 601 forming an ellipse. The first circumferential point A is the closest point to the major axis 300 of the passage opening 30 . The second circumferential point B is the farthest point with respect to the major axis of the passage opening.

As shown in FIG. 4 , the angular coordinates centered on the main axis 300 indicated by the circular angle γ in the plane E1 extend away from the first circumferential point A set as the zero point.

Thus, in a preferred embodiment, as shown in FIG. 4 , the second circumferential point B lies at a circular angle γ of 180° with respect to the first circumferential point A.

Here, the rotational direction of the circular angle γ is clockwise around the center M indicating the main axis 300 .

With respect to the embodiment description, it should be noted that another embodiment is provided in which the cone angle α is designed to vary according to the circular angle γ. Due to this, the tapered inlet area is designed as an oblique inner hollow cone.

3: valve seat
5: Closing element
30: passage opening
41: inlet area
42: middle flow region
43: outlet flow area
70: inner hollow cone
200: flow direction
300: spindle
501: inlet flow cross section
502: intermediate flow section
503: outlet flow cross section
601: inlet circumferential contour
800: cone central axis

Claims (10)

A injector for fluid injection, comprising:
- the valve seat (3) on which a sealing area is arranged, the sealing area being in the shape of a convex recess, a part of the edge of the recess is raised, and
- a closing element (5) arranged on the central axis (XX) of the injector and opening and closing at least one passage opening (30) in the valve seat (3);
- the at least one passage opening (30) comprises a main axis (300) at a set angle (β) with respect to the central axis (XX) of the injector,
- said at least one passage opening (30) comprises an inlet area (41);
- the inlet area 41 is tapered,
the closure element (5) closes the at least one passage opening in contact with the raised edge of the recess, the at least one passage opening (30) being downstream of the sealing area in the flow direction of the fluid; sprayer. The injector according to claim 1, wherein the flow cross-section (501) of the inlet region (41) transverse to the main axis (300) decreases continuously in the flow direction (200). The injector according to claim 2, characterized in that the inlet region (41) is designed as an inner hollow cone (70) with a cone angle (α) of the inner wall with respect to the central axis of the cone (800). The injector according to claim 3, wherein the central axis of the cone (800) intersects the main axis (300) of the passage opening (30) at an angle of inclination (δ). The injector according to claim 3, characterized in that the inlet flow cross section (501) of the inlet region (41), which defines a plane (E1), has a non-circular inlet circumferential contour (601) in the plane (E1). The injector according to claim 5, wherein the inlet circumferential contour (601) is designed to be elliptical in the plane (E1). 7. The inlet circumferential contour (601) according to claim 6, wherein the inlet circumferential contour (601) comprises a first circumferential point (A) closest to the major axis (300) of the passage opening (30) in the plane (E1), the first circumferential point (A) defines a zero circular angle γ in the plane E1 about the main axis 300 , the inlet circumferential contour 601 being the closest to the main axis 300 of the passage opening 30 . and a second distant circumferential point B, wherein the second circumferential point B is arranged at a circular angle γ of 180°, and the cone angle α varies according to the circular angle γ. Engineered, Sandblast. 3. An intermediate flow region (42) according to claim 1 or 2, wherein the passage opening (30) has an intermediate flow cross-section (502) downstream of the inlet region (41) as viewed in the flow direction (200) and an outlet flow section (43) having an outlet flow cross section (503) downstream of the intermediate flow section (42), the intermediate flow section (502) being the narrowest flow cross section of the passage opening (30) . The injector according to claim 8, characterized in that the intermediate flow region (42) and/or the outlet flow region (43) is designed to be cylindrical with respect to the main shaft (300). 9. The inlet region (41) of claim 8, wherein the inlet region (41) has an inlet length (L1), the intermediate flow region (42) has an intermediate length (L2), and the outlet flow region (43) has an outlet length (L3). wherein the inlet length (L1) and the intermediate length (L2) are of similar or equal size to each other, and/or the outlet length (L3) is greater than the inlet length (L1) and/or the intermediate length (L2) 1.3 to 2.3 times the size of an injector.

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